We have found that activation of protein kinase by 8 bromo adenosine 3', 5'-cyclic monophosphate (8 Br-cAMP) in cultured neuroblastoma cells (NB) is followed by preferential phosphorylation of nuclear nonhistone chromosomal proteins and the induction of tyrosine hydroxylase (TH). Our experimental results suggest that TH induction in NB may be preceded by a modulation of gene expression through translocation of protein kinase from cytosol to nucleus and phosphorylation of nuclear nonhistone protein.